1. Technical Field of the Invention
This invention relates to medical implants which can be implanted in the living body for extended periods of time and to the method for the manufacture thereof.
2. Description of the Prior Art
Whether a medical implant, such as a peritoneal catheter, can be successfully implanted in a living body for an extended period of time is highly dependant upon the manner of affixation of said device to the implanted area in the living body. For this reason, various devices are being employed to allow and accelerate the invasion of the living body tissue into the implanted area and thereupon integrate with the implanted device. The conventionally employed method is to provide the circumference of a catheter, for example, with a cuff called a "Dacron.RTM. cuff" which consists of polyester fibers. Alternatively, catheters have been provided with cuffs made from polyurethane sponge or polyethylene sponge.
However, since polyester fibers have lesser ability to effect affixation to the living body, they tend to allow bacteria to invade into the living body, thereby often causing infection. Moreover, neither polyurethane sponge nor polyethylene sponge has provided favorable results in affixation because of their insufficient affinity to the living body. Furthermore, polyurethane sponge, when it has been implanted for a long period, has been found to deteriorate; while polyethylene sponge does not demonstrate any flexibility as a cuff.
A medical implant coated with collagen on its surface for the purpose of enhancing affinity to the living body has been disclosed in Japanese Patent Application (Laid-open) No. 119798/1979. Nevertheless, since mere coating with collagen will not assure that the collagen will become chemically combined with the substrate material, such coated material tends to peel off. To overcome such problems, it was found that the surface of the substrate could be activated by subjecting it to glow discharge or corona discharge before graft polymerizing said surface with acrylic acid so that collagen might react upon the so-modified surface and become chemically combined with the surface. The shortcoming of this method, however, is two fold; one is that it requires costly equipment and the other is uncertainty in uniformly obtaining quality products.
Accordingly, it is an object of this invention to provide medical implants which can be firmly affixed to the living body, thereby enabling the long-term implantation of such medical devices. It is another object of this invention to provide methods for the manufacture of such medical implants.